Dentist&#39;s wedge



Oct. 21, 1969 s. A. ARLERS ET AL. 3,4 73,226

DENTIST'S WEDGE 2 Sheets-Sheet 1 Filed March 22, 1968 FIG! FIG.

Oct. 21, 1969 s. A. ARLERS ET AL 3,

DENTIST'S WEDGE Filed March 22, 1968 2 Sheets-Sheet 2 US. Cl. 32-64 7Claims ABSTRACT OF THE DISCLOSURE A dentists wedge is designed as anelongated body having a cross section essentially like an isoscelestriangle, in which the base is considerably shorter than the two legs.The edges between the base surface and the adjoining side surfaces areconvex and the ridge formed by the adjoining side surfaces is likewiseconvex.

Background of the invention When filling a tooth, not only one-sided ordoublesided cavities in the molar and premolar parts but also in thefront, it is necessary to utilize matrix ribbons which, by means ofwedges, are forced against the tooth to be repaired. The idea is toprevent leakage of saliva into the cavity and filling material awaytherefrom, respectively. An excess of filling material may causeparodontit and secondary caries will soon appear.

It has been proposed to utilize wedges of wood or synthetic resin. Thesewedges have been comparatively short, i.e. the wedge angle is great. Inthis manner only a small part of the wedge will find contact with theteeth when forced into the space therebetween. The wedges usually haverectangular or triangular cross section, and in the latter case thesides are equilateral. Such a wedge will lack stability as it is easilytwisted. Wooden wedges have been made of hard and of soft material. Ahardwood wedge may deform the matrix ribbon and easily works free of thespace between the teeth. A wedge made of soft wood, such as used inmatches, will itself be deformed when forced into the space. Woodenwedges may also be cut from a block to fit the actual need. This is atime consuming job and when utilizing a hard wood the final shaping mustbe done by grinding. It is evident that manually prepared wedges of thistype are far from sterile.

Summary of the invention A correctly shaped wedge shall fulfil thefollowing stipulations.

(1) The cross section of the wedge shall fit the shape of the spacebetween the teeth.

(2) The base surface of the wedge shall preferably be located below thecavity to be filled.

(3) The wedge shall, along its total length, be so designed that it willbe safely retained in the space.

(4) The wedge shall be made of a material which is hard to deform anddoes not swell when coming into contact with saliva.

(5) The material used must be of a kind which has a certain degree ofsoftness and adaptability, but nevertheless has a satisfactoryseparation action.

(6) The wedge must be so designed that an implement for instancetweezers, will obtain a good grip thereof for application as well as forremoval.

(7) The wedge must be able to stand sterilization and preferably be soarranged that it may be removed from a stand without contamination ofother wedges.

The object of the invention is to design a wedge which fulfils thedemands above stated and it is characterized nited States Patent 0 inthe cross section having the shape of an isosceles triangle, in whichthe base is considerably shorter than the legs and in which thelongitudinal edges between the base surface and the adjoining sidesurfaces are convex in relation to the longitudinal axis of the basesurface.

The breadth of the wedge will thus slowly increase in the direction awayfrom the point and finally decrease again, which makes it possible tosecurely retain the wedge. The maximum breadth of the wedge is utilizedto apply a pressure against the portion where a leakage of fillingmaterial is to be expected. By designing the cross section as aisosceles triangle with a comparatively short base the Wedge will obtainsuch a height that it will not yield to twisting.

Brief description of the drawings FIGURE 1 shows on an enlarged scale aview, as seen from above of three teeth, of which the middle one issurrounded by a matrix ribbon. To the right of the tooth this is forcedinto contact with the tooth by means of a wedge of known design, whereasa wedge according to the invention is utilized to the left of the tooth.

FIGURE 2 shows a section along line II-II of FIG- URE 1.

FIGURE 3 shows a wedge according to the invention on an enlarged scale.

FIGURE 4 shows an elevation of the wedge in FIG- URE 3.

FIGURES 5-9 are sections along lines VV, VI-VI, VII-VII, VIIIVIII andDC-IX, respectively, in FIG- URE 4.

FIGURE 10 shows a number of wedges formed integral with a disc, and

FIGURE 11 shows a support stand for a number of wedge carrying discsaccording to FIGURE 10.

Description of the preferred embodiment The novel wedge has across-section shaped like a isosceles triangle in which a base line bcorresponds to a plane base surface 1 of the wedge. This base surface isarranged essentially at right angles to an end surface 3 of the wedgebeing remote from a point 2 thereof. Joint 4 between the two sidesurfaces corresponding to legs a and c of the triangle forms a ridge,the breadth of which successively increases from the point 2 towards theend surface. The ridge is furthermore designed to follow a convex linethe greatest height of which measured from the base surface is locatedcloser to the end surface 3 than to the point 2. Preferably, the maximumheight is located at about one third or one fourth of the lengthmeasured from the end surface. Edges 5 and 6 formed between the basesurface 1 and the side surfaces corresponding to the legs a and 0,respectively, are furthermore slightly convex in relation to thelongitudinal axis of the base surface. The maximum convexity of theedges are preferably located in the portion of the wedge, where themaximum height of the ridge is to be found. The convexity of the edgesof the base surface is preferably so chosen, that part of the basesurface will obtain an essentially constant breadth, with the end of thebase surface close to the point having a lesser breadth that the portionhaving essentially constant breadth. This portion covers about onefourth of the total length of the wedge and is preferably located atabout the middle portion of the wedge. The convex lines form parts ofarcs, the relation of the radius of the ridge 4 in relation to that ofthe edges 5 and 6 being 1:3.

The end surafce 3 of the wedge is continued as an elongated part 7designed as a mounting or handle to be used when the wedge is broughtinto working position or removed therefrom, respectively. This part 7has a cross section the dimensions of which are larger than 3 those ofthe adjacent part of the wedge, with the cross section of the part beingmainly rectangular at this end. The free end of the mounting partextending about halfway the length thereof has a cross-section shaped asan inverted T where the horizontal flanges are coplanar with the basesurface 1.

A number of wedges are formed integral with a disc 9, with the point ofeach wedge being attached to the periphery of the disc in such a mannerthat a wedge may be easily torn ofi? from the disc. This is providedwith a central aperture adapted to be fitted on a support standcomprising a base plate 12 and a stanchion 13, and the latter has such alength that several discs may be fitted thereon. In order to preventturning of the discs in relation to the stanchion when a wedge is to betorn off, each disc is provided with a slot 14 which cooperates with acorresponding key 15 of the stanchion.

The wedges and the discs are made of a synthetic resin of suitablenature for instance a semi-soft styrene resin which may be utilized tobring about a certain separation of the teeth when applied with force.Preferably, the wedges are manufactured with different breadths at thebase surface to fit varying sizes of inter-tooth spaces. Three differentsizes will usually be sufiicient, with each size being made on its owndisc, possibly in different colors and the stand is designed to carry atleast one disc of every size.

FIGURES 1 and 2 show a common situation when wedging a cervical matrixribbon. To the right side of the tooth to be repaired, and which issurrounded by a matrix ribbon 16, a wedge 17 of known design (US. patentspecification 2,867,905) is introduced in the intertooth space. Thiswedge 17 has straight sides, which cannot be brought into contact withthe bulging sides of the tooth. In this way an interstice is formedbetween the ribbon and the tooth which is open downwards and thuspermits entrance of saliva or extrusion of filling material. Such excessof material (vide the arrow in FIGURE 2) will form pockets between thetooth and the gums, which forms nests for bacteria and increases therisk of secondary caries and parodontit.

To the left of the middle tooth in FIGURES l and 2 a wedge according tothe invention is shown. It is evident that the cross section of thewedge completely harmonizes with the shape of the inter-tooth shape. Thebase surface rests against the gums and the side surfaces of the Wedgeabut the matrix ribbons 16 and the juxtaposed tooth, respectively. Theribbon will, due to the action of the wedge, be maintained in a properposition and is given a shape which conforms with the desired contour ofthe tooth. The entrance of saliva is furthermore prevented, whichsimplifies the application of filling material.

As the breadth of the wedge according to the invention slowly increasesin the direction away from the point and thereafter diminishes somewhat,the maximum breadth of the wedge may be utilized for exerting pressurejust at the point where a leakage of filling material may be expected.This point is not always located furthermost in the mesial or distal,but depends on the caries situation. The wedge may furthermore be usedin connection to the restricted mesial surfaces at 4+4, Where fittingsusually are difficult to make.

The wedge has sufiicient height to prevent twisting and the lengththereof is not larger than necessary to permit an easy applicationwithout displacement of the lock for the matrix ribbon, which wouldcause discomfort to the patient.

What We claim is:

1. A dentists wedge comprising an elongated solid body having a crosssection essentially similar to an isosceles triangle, in which the baseis considerably shorter than the legs, the improvement comprising thatthe longitudinal edges between the base surface and the side surfacesare convex in relation to the longitudinal axis of the base surface andthe breadth of the base surface at the end of the wedge remote from thepoint being less than the breadth at the mid portion of the wedge.

2. The dentists wedge according to claim 1 in which the convexity is sochosen, that part of the middle portion of the base surface will obtainan essentially constant breadth.

3. The dentists wedge according to claim 1 in which the convexity is sochosen that part of the base surface will obtain an essentially constantbreadth corresponding to about one fourth of the length of the wedge,the portion extending from about halfway the length thereof, away fromthe point.

4. The dentists wedge according to claim 1 in which the joint betweenthe two side surfaces being opposite to the base surface is rounded anddesigned as a convex ridge, the breadth of the rounded ridge portionsuccessively increasing away from the point.

5. The dentists wedge according to claim 1 in which the joint betweenthe two side surfaces being opposite to the base surfaces is designed asa convex ridge, the greatest height of the rounded ridge being locatedcloser to the end of the Wedge remote from the point than to the pointitself.

6. The dentists wedge according to claim 1 in which the joint betweenthe two side surfaces being opposite to the base surface is designed asa convex ridge, the convexity of the ridge being considerably greaterthan the convexity of the two edges.

7. The dentists wedge according to claim 1 in which the end surface ofthe wedge remote from the tip merges into an extended portion formedintegral with the wedge and shaped to form a handle, the cross sectionof the handle close to the wedge body being larger than the crosssection thereof and of essentially rectangular configuration, and thecross section of the handle portion at the free end thereof, extendingabout halfway the length of the handle portion, being designed as aninverted T, where the horizontal flanges are coplanar with the basesurface of the wedge.

References Cited UNITED STATES PATENTS 2,782,503 2/1957 Thompson 32633,193,094 7/1965 Schulsted 32-64 XR ROBERT PESHOCK, Primary Examiner

